Plant Tropisms

Tropisms

​Auxins

Auxins are a group of plant hormones that play a crucial role in the regulation of plant growth and development. They are primarily involved in promoting cell elongation, particularly in the stems and roots, by loosening cell walls. Auxins also influence the formation of roots, flowers, and fruit by guiding their growth and differentiation. Additionally, they are essential in the process of phototropism and gravitropism, where plants grow in response to light and gravity, respectively.

Dropdown

An auxin is a plant ​

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that regulates growth by promoting cell ​

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and influencing processes like root ​

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, ​

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, and gravitropism.

Fill in the Blanks

Multiple Choice

How do auxins cause a plant to grow toward the light?

• the hormones move to the shaded side causing those cells to multiply and grow

• the hormones move to the sunny side causing those cells to multiply and grow

• the enzymes move to the sunny side causing those cells to multiply and grow

• the enzymes move to the shaded side causing those cells to multiply and grow

Tropisms are directional growth responses in plants triggered by external stimuli, such as light, gravity, water, or touch. Phototropism occurs when plants grow toward or away from light, helping them maximize photosynthesis. Geotropism ensures roots grow downward into the soil for stability and nutrient absorption, while shoots grow upward toward light. Other types include hydrotropism, where roots grow toward water sources, and thigmotropism, where plants respond to physical contact, such as climbing vines wrapping around a support.

Tropisms

Plants respond to gravity. Roots grow down, shoots grow up.

Geotropism

Plants respond to sunlight. Shoots grow toward the light.

​​Phototropism

Plants respond to water. Roots grow toward the water

​​Hydrotropism

Plants respond to touch. Shoots grab onto objects to climb

​​Thigmotropism

Match

Match the following

• Plant Reaction

• water

• light

• gravity

• touch

tropism

hydro

photo

geo

thigmo

• tropism

• hydro

• photo

• geo

• thigmo

Categorize

Options (19)

light

auxin on shadow

water

auxin on dry side

touch

auxin on free side

gravity

plant bending towards light

photoreceptors

root response to water

water availability

climbing

vines

shoot up, root down

Organize these options into the right categories

Phototropism

Hydrotropism

Thigmotropism

Geotropism

Labelling

Label the correct plant tropism.

Drag labels to their correct position on the image

phototropism

hydrotropism

geotropism

thigmotropism

stigmatropism

tripletropism

Multiple Choice

What are the forces that cause plant roots to grow down?

• water and light

• gravity and light

• water and gravity

• gravity only

Multiple Choice

What is the reaction of a venus fly trap catching a fly?

• phototropism

• hydrotropism

• geotropism

• thigmotropism

Multiple Choice

How can hydrotropism be such a bad thing for houses and sidewalks?

• The branches from a tree grow toward the water breaking the roof.

• The roots from a tree grow toward the water breaking the foundation and pipes.

• The roots grow toward the sidewalk when the branches touch the concrete.

• The branches grow toward the sunlight causing the roots to touch the roof.

Multiple Choice

What reaction do sunflowers display during the day?

• Sunflowers follow the flowers because of phototropism.

• Sunflowers follow the tropism because of touching.

• Sunflowers follow the tropism because of gravity.

• Sunflowers follow the sun because of phototropism.